The invention relates to an elliptic valve assembly with compound movement, the novel characteristics of which are that the valve have elliptic heads and in that the motion they describe in the opening and closing process is a combined motion, with a lateral rotation movement in addition to the linear displacement.
The object of the invention is to provide automobile engine manufacturers with a cylinder head with novel valves, in both their configuration and their movement, by which an improved filling of the engine cylinders is obtained as a result of a greater passage section towards the cylinder as compared to conventional valves with a circular head.
In cylinder heads with circular section valves and an opening and closing mechanism implying a linear displacement, it is common that the passage section between the valve and the chamber is limited by the characteristics of the head itself, whether hemispherical, flat or Heron type.
As is known, valves are the closing elements placed between the interior of the cylinders and the inlet and exhaust ducts of the head of an internal combustion engine, so that as any other closing element at the moment when it allows passage it is obstructing the inlet or outlet of the passing fluid, but are necessary to block the connection between the various parts during the remaining cycles.
Conventional valves with a circular head, whether they are driven directly by the cams or by rockers, are mechanical elements with a to-and-fro rocking motion, for which they require two forces to perform their function: one to open, and another to close them returning them to their original closed position.
Once the valve is open it must be closed once again, following the camshaft arrangement, for which a spring is required to exert a force allowing an acceleration identical to that of the lift or displacement to carry out the aforementioned function. In practice the situation is otherwise, as when the valve is lifted the force required must provide the required acceleration to the mass while opposing the action of the spring which will return the valve to its original position.
A number of embodiments exist which are based on different valve systems with alternating motion, among which the following may be cited:
MIESSE engine, with a single pipe for inlet and exhaust which may be used for both by the displacement of a partition in the form of a piston.
SPHINX engine with ring valves, which is actually an improvement on the KNICHT runner, port type.
HEWITT engine, in which the conventional valves are replaced by synchronized pistons.
FISHER engine, which lacks valves but includes ports which in turn are controlled by an ingenious pistons system, which may be seen as a combination of the aforementioned system.
Examples of devices which include valves which, in addition to a linear displacement, also move their head laterally are among others U.S. Pat. No. 4,309,966 and Japanese Patent JP 60006011, although in the first case the valve is circular and in the second it is a perfect ellipse with its head coupled to the shaft in a non-eccentric manner, which prevents the devices disclosed in these documents from providing an ideal passage section and thereby an optimum inlet and exhaust flow to the cylinders.
The valve cylinder head object of the invention provides a solution to the problems presented by conventional valve heads, as in addition to providing new characteristics which result in an improved performance of the engine in which the valve head is installed.
More specifically, the novelty of the cylinder head of the invention is an improved filling of the cylinders, increasing the passage section of conventional valves. That is, using the same mechanical base the innovation of the valve head of the invention lies in an operation similar to that of a runner, with the resulting increased filling of this solution as well as a structural simplicity which can be assimilated in current manufacturing processes without requiring great changes.
This increased passage section by which an improved cylinder fill is attained is achieved by the use of valves with an elliptic head, whose opening and closing motion is complemented by a lateral rotation motion. This latter motion requires the valves to be internally guided by a pair of lugs placed diametrically opposite each other on the corresponding shaft. These lugs move along symmetrical helical tracks made for such purpose in the valve shaft housing, thereby enabling the rotation which is determined to be between 50xc2x0 and 65xc2x0.
To allow the insertion of the valves, the machining of these symmetrical helical tracks which make up the guide will be as far as the bottom end of said valves, and complemented by a metal retainer threaded in the position corresponding to said bottom end in order to prevent leaks through said tracks.
In addition, it should be remarked that the valves are complemented by springs similar to those used in circular valve heads with alternate motion, which springs allow to control the usual opening/closing movement and that of the lateral rotation.
The use of the cylinder head with elliptic valves with compound motion, in accordance with the above, will provide a higher efficiency than any other multi-valve system currently employed, as the application of the system will imply an improved filling of the cylinders; in addition by giving the valves a rotation movement a runner-like passage section is achieved, free of obstacles, allowing the mixture to enter more quickly into the cylinders in the inlet process, thereby allowing a greater sweep of the gases in the exhaust process, thereby achieving their exhaust as well as a greater thermodynamic efficiency.
That is, by achieving an improved filling the volumetric coefficient of the inlet is increased, providing a higher specific power and an improved combustion of the fuel, with the ensuing reduced emission of CO and NO type gases.
Obtaining a higher engine torque at lower revolutions allows manufacturing engines with improved usage capacity at all revolutions.
Considering that the industrialization of the elliptic valve head object of the invention does not require significant changes with respect to current heads, as relates to the size and use of the same movement distribution systems (camshaft), and inlet and exhaust ducts, this will allow a great improvement with a simple application as all other elements are readily applicable as there are no costly innovation processes required in the manufacture production lines.